To learn how to regulate carotenoid content in citrus fruit, we studied the mechanism of carotenoid accumulation using physiological and genetic methods. Based on differences in the carotenoid profiles of flavedo and juice sacs, citrus species could be roughly divided into three groups: carotenoidpoor, violaxanthin-abundant, and b-cryptoxanthin-abundant groups. A comparison of the gene expressi...

Considering the importance of dietary constraints for the widely held view of carotenoid pigmentation as an honest quality indicator, there is surprisingly little data on carotenoid availability in different natural diets or along environmental gradients. Here we investigate the carotenoid availability in the main diet of breeding great tits Parus major , living in urban and rural environments ...

Introduction Available evidence on carotenoid biosynthesis indicates that a general pathway is utilized in all carotenogenic systems, at least in the primary stages (Jensen 1965). The sequential dehydrogenation of the colorless Co precurs~rs to the colored carotenes has been extensively studied in the photosynthe ... t":'"ic----........bacteria (Stanier 1959) and appears to follow the Porter-Li...

The functional role of Adh in regulating susceptibility to abiotic stress and the synthesis of secondary metabolites was investigated in transgenic grapevine plants over- and underexpressing alcohol dehydrogenase (Adh). Plants were transformed with gene constructs containing a sense or antisense orientated grapevine VvAdh2 cDNA under the constitutive cauliflower mosaic virus 35S promoter. Plant...

Carotenoid-based colours are recognized as having an important signalling function, yet the nature of the mechanisms that maintain their honesty is not well understood. By combining a carotenoid-feeding experiment with a quantitative genetic experiment in a wild population of blue tits (Parus caeruleus), we were able to test predictions that differentiate between proposed mechanisms. If variati...

Physiological conditions which lead to changes in total carotenoid content in tomato plantlets were identified. Carotenoid levels were found to increase after the onset of a dark period during a normal 24 h cycle. This rapid initial increase is followed by a steady decrease in carotenoid content throughout the night. A decrease in the expression of several carotenogenic genes, namely pds, zds (...

1. Carotenoids transferred from mother to offspring may enhance the quality of the offspring. Whether such maternal effects occur in guppies ( Poecilia reticulata ) has an important bearing on mate preference evolution. 2. By raising female guppies from birth on different dietary carotenoid levels, we examined the pattern of carotenoid allocation to maternal tissue (skin) vs. eggs. Skin caroten...

In the present study, we experimentally manipulated coccidian parasitism and dietary carotenoid availability in a fully factorial experiment in male house sparrows (Passer domesticus Linnaeus), and tested whether carotenoid supplementation reduces the cost of parasitism in terms of condition, moult and immune responses. We found that coccidians have a significant but transient negative effect o...